Determination of calcium and magnesium ions by colorimetric titration:
- Collect 10 mL of the water to be analyzed and transfer to a 25 mL beaker.
- Add 3 mL of pH 10 buffer solution under an extraction hood and a spatula tip of EBT. The solution takes on a red-purple color.
- Titrate the solution obtained with EDTA at 10-2 mol/L while vigorously stirring the solution.
- The equivalence point is reached when the red-purple color disappears in favor of the blue color of EBT released in solution.
≈ 20 minutes / sample